Summary of Lectures at Japan Welding Society Meeting, 77th series, pages 320 to 321, by Japan Welding Society, September 2005 discloses, for example, that when joining dissimilar metals consisting of steel and aluminum, if silica and oxygen exist at suitable densities in an intermetallic compound reaction layer formed at a joining interface, excess growth of a reaction layer can be suppressed and joining strength can be increased. In particular, by using a steel sheet adjusted so that an inner oxidation is 1.5 μm, a cross tensile strength of 1.4 kN (maximum) can be obtained by electric resistance spot welding and by combining the steel sheet with an aluminum alloy sheet (A6022) 1.6 mm thick.
Summary of Lectures at Japan Welding Society Meeting, 78th series, pages 162 to 163, by Japan Welding Society, April 2006 describes that at the time of spot welding 980 MPa grade alloyed molten zinc-plated steel sheets 1.2 mm thick with an aluminum alloy sheet (A6022) 1.0 mm thick, two-step energization stimulates softening and melting of a plated layer, whereby a wedge-shaped Al3Fe2 intermetallic compound is formed in a reaction interface layer resulting in a high cross tensile strength of 1.2 kN.